"Today's financial results clearly are disappointing," said Chief Executive Gerald Grinstein, whose company has lost more than $9.6 billion since January 2001.

"The issue is simple: Including fuel, Delta is not on plan, but excluding fuel, we are better than plan."

Delta said it doesn't have any hedges in place that would reduce its jet-fuel costs below market prices. Its price for jet fuel climbed to an average of $1.46 a gallon in the quarter, as supply concerns boosted the cost of crude oil, from which the fuel is refined.

The cost of crude oil averaged $50.03 a barrel during the period, up 42 percent from a year earlier.

"Nobody is really geared to operate profitably with these high fuel prices," said Dan Kasper, a Cambridge, Mass.-based airline economist for LEGC LLC.

Delta said its U.S. fare decrease implemented in January isn't stimulating as much passenger traffic as expected. Yield, the best measure of average fares, dropped 7.9 percent.

Northwest, the fourth-biggest domestic carrier, said its first-quarter loss nearly doubled, to $458 million, or $5.28 a share, from $230 million, or $2.67 a share, in the year-ago period.

Excluding one-time charges, the Eagan, Minn.-based carrier lost $5.07 a share, worse than estimates of $4.56 a share.

The nation's six major legacy carriers have lost nearly $33 billion combined over the last four years.

That total could deepen because Elk Grove Township-based United Airlines and US Airways have yet to report their first-quarter results. The other carriers are Delta, Northwest, American Airlines and Continental Airlines.

JetBlue posted net income of $7 million, or 6 cents a share, down from $15.2 million, or 14 cents a share, a year earlier.

The New York-based carrier still beat estimates by 3 cents a share, and CEO David Neeleman said he expects to remain profitable throughout the year. First-quarter traffic as measured by miles flown by paying passengers climbed 31 percent, but JetBlue's yield declined 2.7 percent.

Shares of Delta gained 21 cents, to $3.86, on the New York Stock Exchange.